Ultrasonic bonding



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uct. w, 1966 R. HOFFMAN 3,279,067

ULTRASONIC BONDING Filed March 12, 1963 HIGH GENERATOR INVENTOR. ROBERTHOFFMAN ATTOR NEYJ United States Patent "ice 3,279,067 ULTRASONICBONDING Robert Holfman, 9833 64th Ave., Rego Park, Queens, NY. FiledMar. 12, 1963, Ser. No. 264,573 3 Claims. (Cl. 32-1) This inventionrelates generally to the medical art; more specifically it presents anovel method and process of joining and combining to human tissue; andin detail, it is concerned with the utilization of ultrasonic waves andvibrations for bonding to human tissue.

In the prior art, it is known to utilize mechanical means or at timesadhesive means to bond or adhere any desired substance to human tissue.For example, in the field of dentistry, when filling cavities or inother mouth restoration work, joining materials, such as metals and thelike, are utilized to fit within and around prepared surfaces. The teethsurfaces must be ground so as to permit the material such as amalgam tobe wedged against portions thereof or to project partially therewithin.Although many variations and embellishments of this art are known, theyall utilize the mechanical properties of the material being added tolock to the desired tooth structure. Teeth are but one example of humantissue and similar effects are utilized throughout the medical art forlike purposes.

Of course, these mechanical processes suffer from several well knowndisadvantages. For example, the human tissue must be preparedmechanically to receive and wedge and thereby lock the material to beadded in place. This is not always convenient or even possible andsometimes makes necessary the removal of excess tissue. Additionally,there is no assurance of uniform and even joining of the material beingadded to the tissue. In clinical applications, it is well known that aless than completely uniform joint and interface is often obtained.

This invention contemplates the utilization of ultrasonic waves andvibrations properly coupled to chemically combine the material to beadded and the tissue to provide a more etficient bond and one that maybe obtained directly against the tissue without the necessity ofmechanical wedging, although the same may be utilized, if desired.

The above permits molecular bonding which would be useful. For example,it could be utilized to restore a hard tissue destroyed as a result ofcaries. This could be done without dependence upon the necessarilydefective interfaces presently obtained by surface adaptation or cement.Molecular bonding of restorations would permit the penetration at theinterface of the restoration material with the hard tissue and wouldprovide a thoroughly leak-proof and permanent interface.

Additionally, the new method and process of molecular bonding would beespecially useful in the treating of periodontal disease. The inventionprovides an improved method of affixing a stabilizing appliance.

Additional advantages would be obtained in fields such as orthodonticsand prosthetics and in fact, to all of the other analogous medical arts.

It is a cardinal object of this invention, therefore, to provide amethod and process for bonding a material chemically to human tissue,such as bone, cementum, dentine and enamel.

Another primary object is to set forth an apparatus for convenientlyaccomplishing the above.

With these objects in view, the invention consists of the novel featuresof construction and arrangement of parts which will appear in thefollowing specification and recited in the appended claims, referencebeing had to the accompanying drawings in which the same reference3,279,067 Patented Oct. 18, 1966 numerals indicate the same partsthroughout the various figures and in which:

FIG. 1 is a view in perspective of the instant invention being utilizedfor the purpose of aflixing material to a tooth surface.

FIG. 2 is a diagramatic representation of one form of ultrasonic wavegenerator taken substantially along line 2-2 of FIG. 1.

FIG. 3 is an elevational view partially in section to illustrate theunique bonding obtained according to this invention.

This invention utilizes a high frequency generator to chemically bond tohard human tissue such as teeth.

Although the description set forth hereinafter will refer to teethrestoration, it is to be understood that this invention could equallywell be utilized to bond to any hard human tissue. In such bonding,however, it is important that the material to be added strongly, bond tothe tissue to prevent breakdown and resulting pain, discomfort anddanger to health. For this purpose, ultrasonic vibrations are hereinutilized to chemicaly mix the material to be added such as metal or thelike to the tissue structure.

Elastic waves of frequencies beyond the range of audibility, calledultrasonic or supersonic waves, have been found to produce someinteresting results. If the frequency of the waves is raised to arelatively high degree and coupled properly, they may produce vibrationand thereby physical movement of each molecule comprising a material.Thus, at the interface of two materials in intimate contact that aresupersonically vibrated to a desired extent, there may be a physicalintermixing of some of the molecules of each of the materials with theother, thereby causing a chemical joinder of the two said materials.

There are several well known methods of generating ultrasonic frequencywaves. For example, there are purely magnetic methods includingvibratory components and electronic methods including piezo-electric ormagneto-strictive vibratory systems. The frequencies generated by suchsystems range upward and exceed 200 or 300 kilocycles per second andoften range upward into the megacycle range.

It has been found that when such vibrations are caused to exist betweena material such as a metal, and human tissue, there will be a chemicalmixing of the molecules comprising the metal and those of the humantissue. This is far superior to the joining of a physical nature whichwas heretofore possible.

It is to be emphasized that it is contemplated that the bonding hereinis a true solid-state bond. The wandering of the molecules between thetwo materials being joined is a direct result of the introduction ofelastic vibratoryenergy into the materials being joined.

The invention set forth herein may be especially useful when applied tothe combination of a metal and enamel as commonly found in teeth in thatboth contain a definite crystalline structure.

By way of example, there is illustrated in FIG. 1 dental tissue 10, theenamel of which will require an attachment for dental treatment orrestoration as set forth heretofore. The attachment will be applied to ashield which will be formed from a metal 12 and ultrasonic vibrationswill be utilized to mechanically bond the same to the tooth enamel. Forthe purposes of this description, a hand tool 14 is shown generating thedesired ultrasonic vibrations.

The operation of the exemplary hand tool 14 may be explained byreference to FIG. 2. There is shown in that figure, which is primarilydiagrammatic, the section through the tool 14 showing the outer casing15 thereof and an inner tip of a magnetically attractive material 16.The said tip 16 will extend at least partially through the longitudinalaxis of the casing 15 of the hand tool 14 and will have a tip portion16a extending partially from the front thereof. The central tip 16 willbe surrounded by a plurality of evenly spaced coils of wire 18, 19 and20. The coils of wire 18, 19 and 20 are each connected electrically to arotating oscillator 21 which will act as a high frequency wavegenerator. Each of the coils 18, 19 and 20 will be connected to theoscillator 21 in a fashion electrically spaced relative to the wavesgenerated by the oscillator 21 corresponding to the physical positioningof the said coils about the tip 16.

One end of the tip 16 may be fastened to the hand tool 14 and theremainder thereof including the extending tip portion 16a thereof willbe free to vibrate.

Thus, as the high frequency waves are caused to be rotated about themagnetically attractive tip 16 they will cause the said tip 16 tocorrespondingly vibrate as desired. The amplitude of the viebration willbe dependent upon the strength of the generated rotating magnetic fieldand the rigidity of the said tip 16. However, it will be seen that theextending end tip portion 160 of the hand tool 14 may be caused tovibrate ultrasonically as desired, merely by adjusting the oscillator21.

Of course, it is to be emphasized that the generating means that is setforth herein is shown merely for exemplary purposes and any other wellknown high energy vibratory means may be substituted therefor.

Referring particularly to FIG. 1, there will be described a method ofbonding an attachment to the enamel surface 11. A wire or the like of amaterial to be utilized to form the attaching plate or shield, such asof aluminum, or the like, will be placed on the said dental enamel 11.The ultrasonically vibrating extending tip portion 16a of the hand tool14 will then be urged against the said aluminum 12. The tooth to betreated, however, will be secured in a relatively stationary mannerwithin the mouth. If necessary, this may be accomplished by any suitablestationary and rigid clamp as at 30. Thus, at the intersection 31 of thealuminum 12 and the dental enamel 11, there will be relative vibrationof the two materials at the desired supersonic frequency.

As set forth therein, this will cause a wandering of some of themolecules of each of the materials into the molecules of the othermaterial thus causing a chemical intermixing of the aluminum 12 and thestructure of the tooth 10.

This then provides a bond between the two materials to a degree neverbefore obtainable.

In the illustrated embodiment of the invention, the aluminum material 12will be chemically bonded in a thin film over an area of the dentalenamel 11. This then presents a surface of a metal which may be utilizedfor any desired medical purpose such as for the attachment,

of an appliance 40 for orthodontic use.

It should again be noted that never before was such bonding to a surfaceof dental enamel or other similar tissue possible.

When it is desired to fill a cavity, the hand tool 14 may be heldagainst the aluminum 12 until the said aluminimum entirely fills thecavity. The relative high frequency vibration of the aluminum 12relative to the tooth 10 will cause portions of the said aluminum 12 toflow as would a plastic or liquid material until the said cavity 11 isentirely filled.

It should again be noted that although specific materials are mentionedto be utilized in conjunction with tooth restoration, it is notcontemplated that this invention is to be so limited. It is rathercontemplated that similar bonding in any similar medical application tohuman tissue may be accomplished.

By way of example, chemical bonding such as described hereinabove, totooth enamel, was accomplished using aluminum of a diameter of .005inch. The said aluminum was placed against the labial surface of acentral incisor. Ultrasonic vibrations in the range of kilocycles wereapplied to the aluminum. A high degree of chemical bond was found toexist between the aluminum and the dental enamel.

The device utilized was basically a generator producing the desiredultrasonic frequency supplying a force insensitive transducer. Thetransducer was of the magneto-strictive type. In such a device,electrical waves converted to mechanical vibrations as a result of thetendency of a magnetically attractive rod to increase and decreaseslightly in length as the intensity of the magnetic field varies.

Attached to the transducer was a tip acting as a coupling system totransmit the vibratory energy to the aluminum to be bonded. The tip orcoupler was designed to operate at maximum cfiiciency at its resonantfrequency which was approximately 60 kilocycles per second. The toothwas held in position by a fixed anvil.

While there are above described but a limited number of embodiments ofthe structure and product of the invention herein presented, it ispossible to produce still other embodiments without departing from theinventive concept herein disclosed and it is desired, therefore, thatonly such limitations be imposed on the appended claims as are statedtherein or required by the prior art.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is:

1. The method of attaching a relatively thin piece of metallic materialto relatively hard animal tissue, namely teeth and bone, for medicalpurposes including the steps of, urging said material against saidtissue, and applying ultra-high frequency vibrations to said materialthereby causing said material to vibrate relative to said tissue therebychemically bonding to said tissue.

2. The method of attaching a relatively thin piece of metallic materialto relatively hard animal tissue, namely teeth and bone, for medicalpurposes including the steps of, urging said material against saidtissue, rigidly clamping said tissue thereby preventing any vibrationthereof, and applying ultra-high frequency vibrations to said materialthereby causing said material to vibrate relative to said tissue therebychemically bonding to said tissue.

3. The method of attaching a material to relatively hard animal tissuefor medical purposes as set forth in claim 1, wherein said appliedultra-high frequency vibrations are in the order of sixty kilocycles.

References Cited by the Examiner UNITED STATES PATENTS 1,939,712 12/1933Mahoux 148-129 2,651,148 9/1953 Carwile 12824 3,022,814 2/1962 Bodine15673 3,047,942 8/1962 Schneider et al. 15673 X RICHARD A. GAUDET,Primary Examiner.

ROBERT E. MORGAN, Examiner.

1. THE METHOD OF ATTACHING A RELATIVELY THIN PIECE OF METALLIC MATERIALTO RELATIVELY HARD ANIMAL TISSUE, NAMELY TEETH AND DONE, FOR MEDICALPURPOSES INCLUDING THE STEPS OF, URGING SAID MATERIAL AGAINST SAIDTISSUE, AND APPLYING ULTRA-HIGH FREQUENCY VIBRATIONS TO SAID MATERIALTHEREBY CAUSING SAID MATERIAL TO VIBRATE RELATIVE TO SAID TISSUE THEREBYCHEMICALLY BONDING TO SAID TISSUE.